The central goal of the proposed project is to assess the feasibility of a commercially viable, preventive intervention product aimed at enhancing new fathers' positive adaptation to parenthood. We will integrate an existing evidence-based transition to parenthood program with leading fatherhood promotion curriculum materials, and deliver the intervention content through a multi-component web- based infrastructure with reach to mobile devices. The system will enhance father engagement, parenting quality, and co-parenting support, and reduce substance use, harsh parenting, and interparental conflict- all ultimately leading to positive child developmental and mental health outcomes. Research indicates that fathers contribute to family well-being in multifaceted ways. Positive father engagement with their children and fathers' support of mothers each has unique implications for children's well-being and health. Father engagement also benefits fathers: More engaged fathers tend to live healthier and more socially responsible lives. Although some new fathers reduce levels of antisocial behavior and substance use, this is not true for all fathers. Notably, alcohol and substance abuse represent a significant barrier to positive father engagement and is a risk factor for perpetration of violence towards both children and partners. Supporting men in making a positive adjustment to parenthood would therefore likely lead to reduced levels of substance use, and encouraging men to reduce substance use would likely lead to improved positive engagement with their child and partner. We believe that digital technologies offer an important opportunity for population penetration, but that prior digital initiatives to support faters have not been employed in a comprehensive, thoughtful manner, based on solid understanding of the relevant family developmental science, prevention principles related to behavior and relationship change, and an understanding of the capacities, advantages, and limits of digital technologies. Our team integrates experience in all these areas. AIM 1: To integrate program materials from existing transition-to-parenthood and fatherhood interventions currently on DVD and CD-ROM into a single program, adapting and enhancing materials related to self-regulation and substance use. AIM 2: To develop the web-based infrastructure and portal to deliver the content in Aim 1. AIM 3: To assess the feasibility of the core system with 50 expectant fathers, evaluating the appeal, utilization, and user satisfaction.